Questions About Thegameplay

What should i add to a prison in minecraft?

I'm making a prison zombie apocalypse map in minecraft 360 and it's pretty freaking awesome thr zombies spawn in waves and for each wave you complete you get a block of sand you can use as money etc. There is a spawn room in which you enter a prison cell explaining rules, then there's a tutorial room telling how the map works, then a small jail complex. I don't know what to make thr next room.into, and it can't be the even bigger jail complex because I want that to be the climax of thegameplay experience, but if not that what room can I make with a prison theme next? If you wanna add me to see what I have so far then put that in your answer with your gamertag but I need serious ideas please :D